Telah dilakukan penelitian struktur patahan di Sungai Cinambo, Jatigede, Jawa Barat (9/05/15). Penelitian ini bertujuan untuk mengidentifikasi struktur geologi serta nilai strike dan dip batuan di sepanjang Sungai Cinambo. Dari pengukuran... more
Telah dilakukan penelitian struktur patahan di Sungai Cinambo, Jatigede, Jawa Barat (9/05/15). Penelitian ini bertujuan untuk mengidentifikasi struktur geologi serta nilai strike dan dip batuan di sepanjang Sungai Cinambo. Dari pengukuran menggunakan kompas geologi didapatkan nilai strike dengan tiga kali pengukuran sebesar N 1050 E, N 1070 E dan N 1100 E, dengan dip 370, 360 dan 300 pada stasiun 1 dan 2. Data dikorelasikan dengan sifat-sifat geologi batuan. Hasil interpretasi data menunjukkan adanya struktur patahan yang sebagian berupa sesar naik yang terbentuk akibat proses perlipatan yang juga menyebabkan suatu tekanan dan membentuk struktur antiklinorium di stasiun 8. Kemudian dilakukan pengukuran strike pada sayap selatan sebesar N 1200 E/300, dan sayap utara N 800 E/600. Pengolahan data dilakukan dengan menggambarkan hasil pengukuran ke dalam wulf's net. Hasil interpretasi menunjukkan adanya Plunge, yaitu perpotongan antara sayap utara dan sayap selatan antiklin.

Kata Kunci: Cinambo, Patahan, Antiklin, Strike dan Dip, Plunge.
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A new quantitative interpretation method of self potential anomaly related to geometric-shaped models such as horizontal cylinder, vertical cylinder, and sphere object has been proposed in this paper. This method is based on the concept... more
A new quantitative interpretation method of self potential anomaly related to geometric-shaped models such as horizontal cylinder, vertical cylinder, and sphere object has been proposed in this paper. This method is based on the concept of
solving least-squares algorithm with singular value
decomposition approach which is designed and implemented to calculate the depth, the electric dipole moment, the polarization angle, and the geometric shape factor of self potential anomaly. This approach uses singular value decomposition algorithm to solve non-linear inversion of self potential anomaly. The singular value decomposition algorithm was randomly tested on theoretical synthetic data which was generated by a chosen statistical distribution from a known model with different random noise level. The result shows there is a close agreement between the assumed and calculated parameters. Finally the method validity is tested on the real self potential data anomaly which is obtained from a cylindrical object that was buried at certain depth.
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This study presents evidences for fluid flow manifested as pipe structures in the post-evaporitic overburden characterised from a 3D seismic data from the Levant Basin, offshore central Israel. Interestingly these pipes are genetically... more
This study presents evidences for fluid flow manifested as pipe structures in the post-evaporitic overburden characterised from a 3D seismic data from the Levant Basin, offshore central Israel. Interestingly these pipes are genetically and spatially contextualized east and west of the study area, all rooted in the Messinian evaporite substratum. Pipes in the western group accounts for 83% of the pipe population, are crudely cylindrical, oval to elliptical in planform, with diameter and height ranging ~350-2000 m and
~320-420 m, respectively. Internal configurations within this group varies from chaotic to concave upward reflections diagnostic of fluid induced collapse. Pipes in the eastern group are seepage pipes appearing conical in shape, with height of ~350-510 m and diameter of ~320-420 m. The eastern group pipes are characterized by lack of internal reflectivity and/or disrupted stratal reflections. The western group indicates an episode of fluid flow till the mid-Pliocene, compared to late Pliocene in the eastern group. A conceptual model for the pipes in the western group is proposed to have occurred from subjacent dissolution of the Messinian evaporite under deep-water marine conditions during the Pliocene by vertically focused fluid flow from intra-Messinian realm dissolving the top evaporites and inducing systematic collapse in the overburden, the onset of which may have been triggered by seismicity. Conversely, pipes in the eastern group are proposed to have developed from breaching the top evaporite by pressurized fluids that developed from lateral pressure transfer due to differential loading of the overburden and salt tectonics. These pipe structures may pose a potential risk to deep-water exploration and development. The fluid expulsion phenomena documented in this study has wider implications for the hydrodynamics of many basins where thick evaporite layers are widely developed.
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Cavities located in shallow layers of the subsoil represent a major hazard especially in sites located in town centres. For this reason, it is necessary to determine their location and size in order to evaluate the risk of subsidence and... more
Cavities located in shallow layers of the subsoil represent a major hazard especially in sites located in town centres. For this reason, it is necessary to determine their location and size in order to evaluate the risk of subsidence and to draw up plans for restoration and safety. In this study, electrical resistivity tomography was carried out, both to detect cavities and to test a new inversion algorithm that we developed. The cavities are located in a volcanic formation in a public recreation park where there are municipal buildings. The survey was performed using two different arrays: dipole-dipole and Wenner. A new approach to adopting an initial model and inequality constraints was used and the results from different algorithms were compared. The effective range of the dimensions of cavities was determined in order to make an approximate evaluation of ground stability and any potential subsidence hazard.
Since 2001, researchers at the U.S. Geological Survey (USGS) have teamed with industry partners to explore the commercial applications of the USGS-patented (2001) Marine Induced Polarization (IP) Streamer system that has the ability to... more
Since 2001, researchers at the U.S. Geological Survey (USGS)
have teamed with industry partners to explore the commercial
applications of the USGS-patented (2001) Marine Induced
Polarization (IP) Streamer system that has the ability to
rapidly map very low percentage mineral and metallic particle
distributions on and beneath the seafloor in three dimensions
and with high resolution.
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With the extensive filtering described, the poorly coupled transmitter-receiver dipoles, and the EM coupling issue,
it is not clear to us that the anomalies (Veeken et al, 2009) describe are real.
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Estimation of volume of shale is a crucial step in reservoir characterization. Shale volume is generally estimated using gamma ray logs, as they directly measure shale radioactivity. But it does not mean that other log signatures do not... more
Estimation of volume of shale is a crucial step in reservoir characterization. Shale volume is generally estimated using gamma ray logs, as they directly measure shale radioactivity. But it does not mean that other log signatures do not record the presence of shale, and implies that they are not as easily interpretable as done using only gamma ray logs. In this study a methodology using factor analysis and backpropagation neural network is proposed for the estimation of shale volume using gamma ray logs, density logs, and P-wave velocity. Utilization of several logs gives a better estimation of volume of shale and the accuracy of these techniques is discussed and compared with conventional methods.
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The McArthur Basin represents part of a large intracratonic basins system that evolved throughout the North Australian Craton in the overriding plate of a protracted convergent margin along the southern margin of the craton during the... more
The McArthur Basin represents part of a large intracratonic basins system that evolved throughout the North Australian Craton in the overriding plate of a protracted convergent margin along the southern margin of the craton during the Palaeopterozoic and Mesoproterozoic. Basin initiation is likely to be driven by retreat of a north-dipping subduction trench in response to accretion of the West Australian Craton at ca 1790 Ma (Betts and Giles, 2006). The basins of the north Australian Craton preserve a complex evolution involving discrete episodes of crustal extension and transient basin inversion and regional switches in the extension direction (Betts et al., 2004). The basins are best preserved in the Mount Isa Inlier and the McArthur Basin. In the Mount Isa Inlier, Palaeoproterozoic basins are intensely overprinted by intense shortening associated with the Isan Orogeny. In contrast, contractional overprint throughout the McArthur Basin is mild in comparison.

The evolution of the McArthur Basin spans almost 400 million years between ca 1790 Ma and ca 1400 Ma (Rawlings, 1999) and comprises four stacked basinal packages termed the Redbank Package (ca 1790 Ma-1710 Ma), Goyder package (ca 1710 Ma-1690 Ma), Glyde package (ca 1670 Ma-1600 Ma), Favenc package (1600 Ma – 1570 Ma), and the Wilton package (1500 Ma – 1400 Ma).

The Redbank Package (ca 1790 Ma - 1710 Ma) comprises shallow-marine to fluvial sandstone, and lesser lutite, conglomerate, dolostone and bimodal volcanic and shallow intrusive rocks that display a relatively uniform thickness (2.5-6 kilometres) with little variation in facies architecture over large areas of the McArthur Basin (Rawlings, 1999). Locally, lithostratigraphic packages thin againsts palaeogegraphic highs such as the Murphy Tectonic and Urapunga ridges. The Redbank package is generally flat lying to shallow dipping and forms a layer cake stratigraphy that formed in a southward thickening stratal wedge over an area greater than 1,000,000km3. This has led to interpreted models of subsidence driven by a combination of forbulge or dynamic topography (Scott et al., 2000) in either a intracratonic setting or cratonic platform setting (Rawlings, 2007). The Redbank Package correlates with the Leichhardt Superbasin in the Mount Isa terrane. The Leichhardt Superbasin records protracted period of fault controlled deposition including opening of a large continental rift preserved in the Leichhardt River Fault Trough followed by an episode of north-south extension and the development of overprinting east-west – striking normal faults (O’Dea et al., 1997). Basin deposition was interrupted by a basin inversion event (Betts, 1999), which may correlate with the mid-Tawallah inversion reported by Rogers (1996).

The Goyder package (ca 1710 Ma – 1670 Ma) is spatally restricted to a ~6 km-thick depocentre in the central Walker Fault Zone (northeast Arnhem Land) and comprises dominantly shallow-marine to fluvial sandstone (Rawlings, 1999). The package shows distinct stratal-wedge architecture that thicken towards north-south trending faults, suggesting deposition in fault controlled half-grabens during localised east-west extension. The Goyder package correlates with the sedimentary and volcanic succession of the Calvert Superbasin in the Mount Isa Inlier. The early phase of the Calvert Superbasin sedimentary successions were deposited within half grabens bounded by northeast-striking normal faults during northwest-southeast – directed extension (Betts et al., 1999). During the waning stages of the Calvert Superbasin the regional extension direction switched to a northeast-southwest direction and the development of north-northwest and northwest – trending half grabens that may have continued to evolve during the development of the overlying Isa Superbasin (Gibson et al., 2008).

The Glyde Package (ca 1670 Ma - 1600 Ma) defines a change in facies architecture to a basin characterised by deposition of stromatolitic and evaporitic dolostone, fine-grained siliciclastic sedimentary rocks, with smaller constituents of coarse grained sandstone and tuffs (Rawlings, 1999). The Glyde Package was deposited in shallow to moderately deep-water conditions (Rawling, 1999) and is exposed in the Walker and Batten Fault Zones in the northern and southern McArthur Basin, although geophysical data suggests that the Glyde Package may be more extensive beneath younger packages to the west and south of present day exposures. The Glyde Package is extensively affected by syn-depositional basinal faults evident in geophysical datasets. The pattern of basinal faulting is complex and variable across the basin. For example, in the central Batten Trough, the Glyde package depocentres are controlled by rhombic-shaped sub-basins defined by northwest striking normal faults and north-south to north-northeast striking sidewall faults. In the northern Batten Trough the distribution of the Glyde package appears to be controlled by linear northwest-striking basins bounded normal faults. Locally, basin depocentres appear at the intersection of major north-south trending faults (e.g., Emu Fault Zone) and east-west trending faults (e.g., Etheridge and Wall, 1994) which may have acted as extensional faults (Neudert and McGeough, 1996), controlling local facies variations, and produced stratal wedges of the upper Umbolooga Subgroup, which thickened to the east and north-east. On a more regional scale, northwest trending normal faults such as the Mallapunyah Fault (and it’s along strike extension) bound major depocentres to the southwest. We speculate that the Glyde Package fills these depocentres based on the influence of northwest-trending faults on basin architecture to the Glyde package distribution. The pattern of faults activity during the Glyde Package is consistent with northeast-southwest extension. The Glyde package has been correlated with the stratigraphy deposited in the Isa Superbasin (Southgate et al. 2000). Gibson et al., (2008) reported syn-sedimentary faulting and half graben formation associated with approximately northeast-southwest – directed extension which continued until ca 1640 Ma. In the northern Mount Isa terrane, the Isa Superbasin experienced a basin inversion associated with north-south shortening at ca 1640 Ma. Structures formed during this inversion have not been documented in the McArthur Basin, although the inversion may be recorded by the unconformity that seperates the Umbolooga Subgroup and the Batten Subgroup (Jackson et al., 1987).

The Favenc package (ca 1600–?1570 Ma) outcrops from the southern McArthur Basin to northeast Arnhem Land and comprises ~50–1600 metres thick package of stromatolitic and evaporitic dolostone and intercalated sandstone succession deposited in a shallow and, marginal marine, peritidal-shelf and continental sabkha setting (Rawlings 1999). The Favenc package shows little evidence for fault controlled deposition and is interpreted to represent the sag-phase evolution of the basin (Rawlings, 1999). The Favenc package correlates with the upper stratigraphic successions of the Isa Superbasin. Deposition of the Favenc package is coincident with the onset of the Isan Orogeny (Betts et al., 2006), and the development of negative and positive flower structures associated with west-northwest strike-slip faults and northeast – striking splays associated with east-southeast wrenching (Scott et al., 1998). Post-Favenc crustal shortening resulted in thrust duplication of the Redbank and Glyde packages (e.g., Batten Ranges) and has been interpreted to have occurred during east-southeast to west-northwest shortening (Rawlings et al., 1997). Under this kinematic regime, major northwest - striking faults would have undergone sinistral reactivation, whereas the approximately north-south – striking faults would have reactivated as reverse and/or thrust faults. This shortening event correlates with the main phase of east-west shortening of the Isan Orogeny in the Mount Isa Inlier.
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The basement rocks of the poorly understood Thomson Orogen are concealed by mid-Paleozoic to Upper Cretaceous intra-continental basins and direct information about the orogen is gleaned from sparse geological data. Constrained potential... more
The basement rocks of the poorly understood Thomson Orogen are concealed by mid-Paleozoic to Upper Cretaceous intra-continental basins and direct information about the orogen is gleaned from sparse geological data. Constrained potential field forward modelling has been undertaken to highlight key features and resolve deeply sourced anomalies within the Thomson Orogen. The Thomson Orogen is characterised by long-wavelength and low-amplitude geophysical anomalies when compared with the northern and western Precambrian terranes of the Australian continent. Prominent NE- and NW-trending gravity anomalies reflect the fault architecture of the region. High-intensity Bouguer gravity anomalies correlate with shallow basement rocks. Bouguer gravity anomalies below –300 µm/s2 define the distribution of the Devonian Adavale Basin and associated troughs. The magnetic grid shows smooth textures, punctuated by short-wavelength, high-intensity anomalies that indicate magnetic contribution at different crustal levels. It is interpreted that meta-sedimentary basement rocks of the Thomson Orogen, intersected in several drill holes, are representative of a seismically non-reflective and non-magnetic upper basement. Short-wavelength, high-intensity magnetic source bodies and colocated negative Bouguer gravity responses are interpreted to represent shallow granitic intrusions. Long-wavelength magnetic anomalies are inferred to reflect the topography of a seismically reflective and magnetic lower basement. Potential field forward modelling indicates that the Thomson Orogen might be a single terrane. We interpret that the lower basement consists of attenuated Precambrian and mafic enriched continental crust, which differs from the oceanic crust of the Lachlan Orogen further south.
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The basement rocks of the poorly understood Thomson Orogen are concealed by mid-Paleozoic to Upper Cretaceous intra-continental basins and direct information about the orogen is gleaned from sparse geological data. Constrained potential... more
The basement rocks of the poorly understood Thomson Orogen are concealed by mid-Paleozoic to Upper Cretaceous intra-continental basins and direct information about the orogen is gleaned from sparse geological data. Constrained potential field forward modelling has been undertaken to highlight key features and resolve deeply sourced anomalies within the Thomson Orogen. The Thomson Orogen is characterised by long-wavelength and low-amplitude geophysical anomalies when compared with the northern and western Precambrian terranes of the Australian continent. Prominent NE- and NW-trending gravity anomalies reflect the fault architecture of the region. High-intensity Bouguer gravity anomalies correlate with shallow basement rocks. Bouguer gravity anomalies below ~300 mm/s2 define the distribution of the Devonian Adavale Basin and associated troughs. The magnetic grid shows smooth textures, punctuated by short-wavelength, high-intensity anomalies that indicate magnetic contribution at different crustal levels. It is interpreted that meta-sedimentary basement rocks of the Thomson Orogen, intersected in several drill holes, are representative of a seismically non-reflective and non-magnetic upper basement. Short-wavelength, high-intensity magnetic source bodies and colocated negative Bouguer gravity responses are interpreted to represent shallow granitic intrusions. Long-wavelength magnetic anomalies are inferred to reflect the topography of a seismically reflective and magnetic lower basement. Potential field forward modelling indicates that the Thomson Orogen might be a single terrane. We interpret that the lower basement consists of attenuated Precambrian and mafic enriched continental crust, which differs from the oceanic crust of the Lachlan Orogen further south.
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Ce texte présente les résultats préliminaires d’un projet de recherche qui prétend reconstruir l’enquadrement immédiat d’un établissement rural de la région de la Cova da Beira (Portugal), durant le Haut Empire. On prétend ainsi étendre... more
Ce texte présente les résultats préliminaires d’un projet de recherche qui prétend reconstruir l’enquadrement immédiat d’un établissement rural de la région de la Cova da Beira (Portugal), durant le Haut Empire. On prétend ainsi étendre la connaissance du quotidien de ses habitants au-delà des portes de l’édifice qui les a hébergés.

L’objet d’étude est le site de Terlamonte I (Teixoso, Covilhã), dont l’espace habitationnel a été précédemment fouillé au long de plusieurs campagnes archéologiques, dans le quadre du projet “Le peuplement rural romain de la Cova da Beira”.
Cette nouvelle analyse du site a comme particularité le fait de s’intéresser au voisinage immédiat du site, avec une aire d’étude de 2,5 hectares et de recourrir a une stratégie multidisciplinaire, ayant pour objectif l’identification et la compréhension de l’anthropisation de tout cet espace. Des instruments de recherche, comme la prospection de surface en carreaux et la prospection géomagnétique, ont été complétés par une campagne de sondages archéologiques, qui ont permis le prélèvement d’échantillons ultérieurement soumis à des analyses radiométriques et géoarchéologiques. Un système d’information géographique intra-site a faculté l’analyse intégrée des résultats de ces différentes approches.

La présentation des premiers résultats de cette recherche, encore en cours, sert de prétexte à une discussion du contribut, des perspectives et des limites de ces différentes méthodes dans le quadre de la connaissance du peuplement rural romain.
Blog Archéorient
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Resumen: Se describe, a través de diversos ejemplos, la aplicación de las técnicas sísmicas y electromagnéticas marinas en la investigación arqueológica. Dichas técnicas no sólo permiten la localización de yacimientos o hallazgos aislados... more
Resumen: Se describe, a través de diversos ejemplos,
la aplicación de las técnicas sísmicas y electromagnéticas
marinas en la investigación arqueológica.
Dichas técnicas no sólo permiten la localización
de yacimientos o hallazgos aislados sino que, además,
facilitan el análisis del medio marino en el que
éstos se inscriben proporcionando al investigador
información real que permitirá su estudio y posterior
recuperación y/o conservación.
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On February 15, 2015, a magnetometer survey was performed on four test areas at the site of Camp Lawton on Magnolia Springs State Park property. The goal of the survey was to identify subsurface targets and artifacts associated with the... more
On February 15, 2015, a magnetometer survey was performed on four test areas at the site of Camp Lawton on Magnolia Springs State Park property. The goal of the survey was to identify subsurface targets and artifacts associated with the Confederate occupation that occurred in October-November 1864. The survey successfully identified numerous magnetic anomalies that represent possible buried features and clusters of artifacts. While some of these undoubtedly are associated with the mid-20th century CCC occupation at the site, future testing will determine which of these, if any, are associated with the Civil War era occupation.
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